Re: Suspected regression in "x86: extend e820 ealy_res support 32bit"

From: Johannes Weiner
Date: Wed May 21 2008 - 19:14:54 EST


Hi,

"Yinghai Lu" <yhlu.kernel@xxxxxxxxx> writes:

> On Wed, May 21, 2008 at 11:19 AM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>> I'm seeing a crash in current x86.git tip/auto-latest when booting under
>> Xen. The crash is rather early, but it's in __alloc_bootmem_core() in the
>> final memset clear. Apparently the allocator is returning a bad page.
>>
>> This points to changes in the setup of the bootmem allocator, and the
>> changes "x86: extend e820 ealy_res support 32bit" make to
>> arch/x86/kernel/setup_32.c:setup_bootmem_allocator() looks like the most
>> likely suspect. Unfortunately its a rather large patch which is not easy to
>> revert, so I haven't actually confirmed this yet.
>
>
> thanks. please check the attached patch
>
> YH
>
> [PATCH] x86: bootmap size fix for 32 bit
>
> Jeremy Fitzhardinge found
> x86: extend e820 ealy_res support 32bit
> cause regression...
>
> in setup_bootmem_allocator
>
> Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
>
> diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
> index f38d840..938c7b3 100644
> --- a/arch/x86/kernel/setup_32.c
> +++ b/arch/x86/kernel/setup_32.c
> @@ -566,17 +566,22 @@ static void __init relocate_initrd(void)
>
> void __init setup_bootmem_allocator(void)
> {
> + unsigned long bootmap_pages;
> unsigned long bootmap_size, bootmap;
> /*
> * Initialize the boot-time allocator (with low memory only):
> */
> - bootmap_size = bootmem_bootmap_pages(max_low_pfn)<<PAGE_SHIFT;
> + bootmap_pages = bootmem_bootmap_pages(max_low_pfn)<<PAGE_SHIFT;

Forgot to remove the shift?

> bootmap = find_e820_area(min_low_pfn<<PAGE_SHIFT,
> - max_low_pfn<<PAGE_SHIFT, bootmap_size,
> + max_low_pfn<<PAGE_SHIFT,
> + bootmap_pages<<PAGE_SHIFT,

Because this value is hardly sane anymore.

> PAGE_SIZE);
> if (bootmap == -1L)
> panic("Cannot find bootmem map of size %ld\n", bootmap_size);
> bootmap_size = init_bootmem(bootmap >> PAGE_SHIFT, max_low_pfn);
> + printk(KERN_INFO " bootmap [%016lx - %016lx] pages %lx\n",
> + bootmap, bootmap + bootmap_size - 1,
> + bootmap_pages);
> register_bootmem_low_pages(max_low_pfn);
> early_res_to_bootmem(0, max_low_pfn<<PAGE_SHIFT);
> reserve_bootmem(bootmap, bootmap_size, BOOTMEM_DEFAULT);

Besides, what did you want to accomplish?

Hannes
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/